Gas bills can confuse customers, Which? says
A consumer group has urged energy companies to follow the lead of Npower by making bills clearer for customers.
Npower is introducing a new style of bill which includes a "jargon buster" section and a clearer explanation of how the amount was calculated.
Now the consumers' association Which?, which ranked Npower bottom of a customer satisfaction survey in 2009, said others should follow suit.
The energy regulator has told suppliers to make direct debit bills clearer.
Npower, which has 6.6 million UK customers, said its new bill would include a front-page summary including a customer number, how much is owed by or to the customer, whether the bill is an estimate or a meter reading, and emergency contact details.
kWh: Kilowatt hours - the standard measurement on an energy bill that shows your usage
Calorific value: The quality of gas, showing the amount of energy created from burning the gas
Primary/secondary units: You are billed more for primary units, and move on to cheaper secondary units when these are used up
mpan: The 21-digit unique electricity meter point administration number
mprn: Unique gas meter number, irrespective of your supplier
The company said the new bill had been given the thumbs up by the Plain English Campaign.
It also contains a run-down of technical jargon, which the company described as "unavoidable".
"Our discussions with customers and stakeholders have told us that people want their energy bills to be clearer and simpler," said Chris Johnson, of Npower.
"They want to know how much they have to pay and how that amount has been calculated."
More to follow?
Gas and electricity bills are widely regarded as more difficult to understand than other household bills, such as credit card and mobile phone demands.
In March 2009, regulator Ofgem told energy companies to make monthly direct debit demands clear to customers.
It said suppliers were not systematically getting bills wrong but that they should make charges more transparent.
Various consumer groups have encouraged companies to make them clearer.
"Which? has complained for years that many consumers are left scratching their heads trying to work out how their energy bill was calculated," said Which? chief executive Peter Vicary-Smith.
"We are delighted that Npower has responded to our concerns by making its bills much clearer, and we want other energy suppliers to follow suit."
Npower had particular reason for taking the lead among the biggest energy companies, having finished bottom of the list of the six big energy suppliers in a Which? customer satisfaction survey.
The survey, of 2,708 customers, found Scottish and Southern Energy and E.On had the highest approval rating, but still only 29% of their customers were satisfied with how gripes were dealt with.
It also finished bottom of another satisfaction survey in October run by Which? which compared the "big six" with smaller energy suppliers.
Separately, every UK energy customer will have received an annual statement for the first time from their energy supplier by the end of 2010.
These statements are aimed at ensuring the 200 million bills sent by energy companies each year are more understandable.